This patch adds the ability to chain multiple trace entries together to
extend the size of the argument buffer. This means that a tracepoint is
no longer limited to the size of a single entry, so it can have any
number of arguments, and their size is also not constrained to a single
entry.
Some limitations are still there: a tracepoint can have up to 5
arguments and strings are limited to 255 bytes. These constraints stem
from the definitions of tracepoint structures, which could be easily
modified to extend the limits if needed.
To record a tracepoint requiring larger buffer, aside from reserving
`spdk_trace_entry` structure, a series of `spdk_trace_entry_buffer`
structures are allocated too. Each of them acts as a buffer for the
arguments. To allow trace tools to treat the buffer structures
similarly to regular entries, they also have the `tpoint_id` and `tsc`
fields. The id is always assigned to `SPDK_TRACE_MAX_TPOINT_ID` to make
sure that a buffer is never mistaken for an entry, while the value of
`tsc` is always shared with the initial entry. This also provides a way
for the trace tools to verify if an entry is part of a chained buffer.
Signed-off-by: Konrad Sztyber <konrad.sztyber@intel.com>
Change-Id: I51ceea6b6e57df95d4b8bd797f04edbc4936c180
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/8405
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ziye Yang <ziye.yang@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
6cc3169677